system development methodology, database management system, database design paradigm, data definition language, command language, system interface, user interface, technology, or media for an archive to be compliant. Its aim is to set the standard for the activities that are involved in preserving a digital archive rather than the method for carrying out those activities. The acronym OAIS should not be confused with OAI, which is the Open Archives Initiative. The reference model The reference model: provides a framework for the understanding and increased awareness of archival concepts needed for long term digital information preservation and access. provides the concepts needed by non-archival organizations to be effective participants in the preservation process. provides a framework, including terminology and concepts, for describing and comparing architectures and operations of existing and future archives. provides a framework for describing and comparing different long term preservation strategies and techniques. provides a basis for comparing the data models of digital information preserved by Archives and for discussing how data models and the underlying information may change over time. provides a foundation that may be expanded by other efforts to cover long-term preservation of information that is not in digital form (e.g., physical media and physical samples). expands consensus on the elements and processes for long-term digital information preservation and access, and promotes a larger market which vendors can support. guides the identification and production of OAIS-related standards. Requirements of the system The reference model ( ISO 14721:2003) includes the following responsibilities that an OAIS archive must abide by: Negotiate for and accept appropriate information from information Producers. Obtain sufficient control of the information provided to the level needed to ensure Long-Term Preservation. Determine, either by itself or in conjunction with other parties, which communities should become the Designated Community and, therefore, should be able to understand the information provided. Ensure that the information to be preserved is Independently Understandable to the Designated Community. In other words, the community should be able to understand the information without needing the assistance of the experts who produced the information. Follow documented policies and procedures which ensure that the information is preserved against all reasonable contingencies, and which enable the information to be disseminated as authenticated copies of the original, or as traceable to the original. Make the preserved information available to the Designated Community. The OAIS environment and information model The OAIS environment involves the interaction of four entities: